Indoor navigation in a location presents a problem compared to outdoor navigation, in that satellite signals used in calculating a position within the location, through the use of a global navigation satellite system, are significantly attenuated by the structure of the building. A method for enabling indoor navigation using variations in the magnetic field of the location is known from U.S. Pat. Nos. 8,798,924 and 9,078,104.
However, the method for enabling indoor navigation using variations in the magnetic field of the location, due to ferromagnetic influences causing variations in the native Earth's magnetic field (EMF), suffers from a number of shortcomings.
Firstly, two or more paths through the area that has been magnetically mapped may produce the same or very similar variations in the magnetic field vectors along the path, in which case the navigation system will be unable to reliably determine which path has been followed, and as a result an actual position and a path traversed cannot be established.
Secondly, in large empty open areas such as aircraft hangers or factory floors there may not be enough ferromagnetic materials in the vicinity of the paths to produce measurable differences between the magnetic fields along the paths.
Thirdly, with current magnetic field based navigation methods the magnetic field measuring device must move through the location's field in order to establish a pattern of magnetic field changes to determine position, and the method is therefore of no use in determining a position when the magnetic field measuring device is stationary,
Finally, area to be navigated may experience irregular changes in the alterations to the magnetic field due to the addition or removal of ferromagnetic materials, for example in an underground garage or aircraft hanger, where vehicles may be parked and then removed at unpredictable intervals.
It is the intention of the present invention to address the shortcomings of the prior art, i.e. the problems of determining an indoor position using fluctuations in the magnetic field strength and direction over an area, in a location where no significant magnetic field fluctuations may be detected, where multiple locations within the area to be navigated present the same alterations in magnetic field strengths, where the magnetic field measuring device is stationary, or where noticeable changes to the magnetic field strength occur at unknown intervals.